Gas turbine engine geared architecture axial retention arrangement

ABSTRACT

A support assembly for a geared architecture includes an engine static structure. A flex support is secured to the engine static structure and includes a bellow. A support structure is operatively secured to the flex support. A geared architecture is mounted to the support structure. First members are removably secured to one of the engine static structure and the flex support and second members are removably secured to the support structure. The first and second members are circumferentially aligned with one another and spaced apart from one another during a normal operating condition. The first and second members are configured to be engageable with one another during an extreme event to limit axial movement of the geared architecture relative to the engine static structure.

This application is a continuation application of U.S. patentapplication Ser. No. 13/435,353, which was filed on Mar. 30, 2012.

BACKGROUND

This disclosure relates to limiting axial movement of a gearedarchitecture within a turbomachine during an extreme event.

Turbomachines, such as gas turbine engines, typically include a fansection, a turbine section, a compressor section, and a combustorsection. Turbomachines may employ a geared architecture connecting thefan section and the turbine section.

Support structures are used to hold the geared architecture within theturbomachine. The support structures may be relatively compliant toaccommodate some movement of the geared architecture relative to otherportions of the turbomachine. Extreme engine events such as fan bladeloss or failure of fan shaft bearing supports may encourage significantaxial movement of the geared architecture and the fan, relative to otherportions of the turbomachine. These movements are undesirable as isknown. The relatively compliant support structures may not providedesired axial retention of the geared architecture during extreme engineevents.

SUMMARY

In one exemplary embodiment, a support assembly for a gearedarchitecture includes an engine static structure. A flex support issecured to the engine static structure and includes a bellow. A supportstructure is operatively secured to the flex support. A gearedarchitecture is mounted to the support structure. First members areremovably secured to one of the engine static structure and the flexsupport and second members are removably secured to the supportstructure. The first and second members are circumferentially alignedwith one another and spaced apart from one another during a normaloperating condition. The first and second members are configured to beengageable with one another during an extreme event to limit axialmovement of the geared architecture relative to the engine staticstructure.

In a further embodiment of any of the above, the flex support includesan end opposite the bellow. The first members are removably secured tothe end.

In a further embodiment of any of the above, the end is an annularmounting flange.

In a further embodiment of any of the above, the support structureincludes a torque frame and a carrier. The second members are removablysecured to at least one of the torque frame and the carrier.

In a further embodiment of any of the above, the support structureincludes a lubrication manifold. The second members are removablysecured to the carrier and the lubrication manifold.

In a further embodiment of any of the above, the lubrication manifold isarranged axially between the carrier and the second member, engaging thelubrication manifold.

In a further embodiment of any of the above, threaded fastenersremovably secure the first and second members to the flex support andthe support structure.

In one exemplary embodiment, a method of retrofitting a support assemblyto a gas turbine engine having a geared architecture includes the stepsof providing attachment features in first and second structures,securing first and second members respectively to the first and secondstructures arranging the first and second members in axially spacedrelation to one another in an installed condition, and installing thefirst structure onto an engine static structure and a gearedarchitecture onto the second structure.

In a further embodiment of any of the above, the attachment featureproviding step includes providing machined surfaces on the first andsecond structures.

In a further embodiment of any of the above, the first structure is aflex support having a bellow and an annular mounting flange opposite thebellow. The securing step includes mounting the first members to theannular mounting flange.

In a further embodiment of any of the above, the securing step includesmounting a lubrication manifold onto the second structure and securingthe second members over the oil manifold.

In a further embodiment of any of the above, the installing stepincludes securing a torque frame to the flex support and a carrier. Thecarrier supports the geared architecture.

In a further embodiment of any of the above, the arranging step includespositioning the first and second members in a first angular positionrelative to one another, and rotating the first and second members fromthe first angular position to a second angular position against a stop.

In a further embodiment of any of the above, the securing steps includetightening threaded fasteners.

In a further embodiment of any of the above, the securing step relatingto the second members includes selecting fasteners having a lengthlonger than a length of pre-exiting fasteners at the attachment feature,which are removed during retrofitting.

In one exemplary embodiment, a gas turbine engine includes an enginestatic structure. A flex support is secured to the engine staticstructure and includes a bellow. A support structure is operativelysecured to the flex support A geared architecture is mounted to thesupport structure. A fan section is operatively coupled to the gearedarchitecture. First members are removably secured to one of the enginestatic structure and the flex support, and second members are removablysecured to the support structure. The first and second members arecircumferentially aligned with one another and spaced apart from oneanother during a normal operating condition. The first and secondmembers are configured to be engageable with one another during anextreme fan section event to limit axial movement of the gearedarchitecture relative to the engine static structure.

In a further embodiment of any of the above, the gas turbine engineincludes low and high spools. Low pressure compressor and turbinesections are mounted on the low spool and high pressure compressor andturbine sections are mounted on the high spools. The low spool isoperatively coupled to the geared architecture.

In a further embodiment of any of the above, the geared architecture isa planetary gear train.

In a further embodiment of any of the above, the fan section includes afan shaft supporting a fan. The fan shaft is supported relative to theengine static structure by bearings.

In a further embodiment of any of the above, the gas turbine engineincludes threaded fasteners that removably secure the first and secondmembers to the flex support and the support structure.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure can be further understood by reference to the followingdetailed description when considered in connection with the accompanyingdrawings wherein:

FIG. 1 shows a partial section view of an example gas turbine engine.

FIG. 2A depicts a highly schematic view of an example gearedarchitecture support assembly of the FIG. 1 gas turbine engine duringnormal operation.

FIG. 2B depicts a highly schematic view of the FIG. 2A gearedarchitecture support during an extreme event.

FIG. 3 is a cross-sectional view of a geared architecture and an examplesupport assembly during normal operation.

FIG. 4 is a rear view of an example oil manifold of the supportassembly.

FIG. 5 is a front view of an example flex support of the supportassembly.

FIG. 6A is a front view of the oil manifold and flex support in a firstangular position during assembly.

FIG. 6B is a top elevational view of the support assembly in the firstangular position.

FIG. 7 is a front view of the oil manifold and flex support in a secondangular position after assembly.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates a gas turbine engine 20. The gasturbine engine 20 is disclosed herein as a two-spool turbofan thatgenerally incorporates a fan section 22, a compressor section 24, acombustor section 26 and a turbine section 28. Alternative engines mightinclude an augmentor section (not shown) among other systems orfeatures. The fan section 22 drives air along a bypass flowpath B whilethe compressor section 24 drives air along a core flowpath C forcompression and communication into the combustor section 26 thenexpansion through the turbine section 28. Although depicted as aturbofan gas turbine engine in the disclosed non-limiting embodiment, itshould be understood that the concepts described herein are not limitedto use with turbofans as the teachings may be applied to other types ofturbine engines including three-spool architectures.

The engine 20 generally includes a low speed spool 30 and a high speedspool 32 mounted for rotation about an engine central longitudinal axisA relative to an engine static structure 36 via several bearing systems38. It should be understood that various bearing systems 38 at variouslocations may alternatively or additionally be provided.

The low speed spool 30 generally includes an inner shaft 40 thatinterconnects a fan 42, a low pressure (or first) compressor section 44and a low pressure (or first) turbine section 46. The inner shaft 40 isconnected to the fan 42 through a geared architecture 48 to drive thefan 42 at a lower speed than the low speed spool 30. The high speedspool 32 includes an outer shaft 50 that interconnects a high pressure(or second) compressor section 52 and high pressure (or second) turbinesection 54. A combustor 56 is arranged between the high pressurecompressor 52 and the high pressure turbine 54. A mid-turbine frame 57of the engine static structure 36 is arranged generally between the highpressure turbine 54 and the low pressure turbine 46. The mid-turbineframe 57 supports one or more bearing systems 38 in the turbine section28. The inner shaft 40 and the outer shaft 50 are concentric and rotatevia bearing systems 38 about the engine central longitudinal axis A,which is collinear with their longitudinal axes. As used herein, a “highpressure” compressor or turbine experiences a higher pressure than acorresponding “low pressure” compressor or turbine.

The core airflow C is compressed by the low pressure compressor 44 thenthe high pressure compressor 52, mixed and burned with fuel in thecombustor 56, then expanded over the high pressure turbine 54 and lowpressure turbine 46. The mid-turbine frame 57 includes airfoils 59 whichare in the core airflow path. The turbines 46, 54 rotationally drive therespective low speed spool 30 and high speed spool 32 in response to theexpansion.

The engine 20 in one example is a high-bypass geared aircraft engine. Ina further example, the engine 20 bypass ratio is greater than about six(6), with an example embodiment being greater than ten (10), the gearedarchitecture 48 is an epicyclic gear train, such as a star gear systemor other gear system, with a gear reduction ratio of greater than about2.3 and the low pressure turbine 46 has a pressure ratio that is greaterthan about 5. In one disclosed embodiment, the engine 20 bypass ratio isgreater than about ten (10:1), the fan diameter is significantly largerthan that of the low pressure compressor 44, and the low pressureturbine 46 has a pressure ratio that is greater than about 5:1. Lowpressure turbine 46 pressure ratio is pressure measured prior to inletof low pressure turbine 46 as related to the pressure at the outlet ofthe low pressure turbine 46 prior to an exhaust nozzle. It should beunderstood, however, that the above parameters are only exemplary of oneembodiment of a geared architecture engine and that the presentinvention is applicable to other gas turbine engines including directdrive turbofans.

A significant amount of thrust is provided by the bypass flow B due tothe high bypass ratio. The fan section 22 of the engine 20 is designedfor a particular flight condition—typically cruise at about 0.8 Mach andabout 35,000 feet. The flight condition of 0.8 Mach and 35,000 ft, withthe engine at its best fuel consumption—also known as “bucket cruiseThrust Specific Fuel Consumption (‘TSFC’)”—is the industry standardparameter of lbm of fuel being burned per hour divided by lbf of thrustthe engine produces at that minimum point. “Fan pressure ratio” is thepressure ratio across the fan blade alone, without a Fan Exit Guide Vane(“FEGV”) system. The low fan pressure ratio as disclosed hereinaccording to one non-limiting embodiment is less than about 1.45. “Lowcorrected fan tip speed” is the actual fan tip speed in ft/sec dividedby an industry standard temperature correction of [(Tambient degR)/518.7)^0.5]. The “Low corrected fan tip speed” as disclosed hereinaccording to one non-limiting embodiment is less than about 1150ft/second.

A fan shaft 60 interconnects the geared architecture 48 to the fan 42.The fan shaft 60 is supported by a pair of bearings 38, which aretapered roller bearings in one example. The bearings normally limit theaxial travel of the fan shaft 60 and fan 42. During operation, theengine 20 may experience extreme events such as a fan blade loss or afailure of a fan shaft bearing support 62 supporting the bearings 38,which is part of the engine static structure 36. In such events, the fan42 may undesirably tend to move axially forward relative to the otherportions of the engine 20, such that the fan 42 and associatedcomponents could become disengaged from the engine 20.

Referring to FIGS. 2A and 2B with continuing reference to FIG. 1, theexample engine 20 includes other features that limit movement of the fan42 during an extreme event, particularly if the bearings 38 or bearingsupport 62 are ineffective. For example, the example engine 20 includesa geared architecture support assembly 64 that limits forward movementof the fan 42 and the geared architecture 48 during an extreme event.

The example support assembly 64 includes at least a first member 66 anda second member 68. The first member 66 and the second member 68 arerespectively operatively connected to the geared architecture 48 and theengine static structure 36, which functions as a mechanical ground. Acompliant flex support 70 mounts the geared architecture 48 to theengine static structure 36. In the example, the first member 66 and thesecond member 68 are both arranged axially aft the geared architecture48 relative to a direction of flow through the engine 20.

During normal engine operation, the first and second members 66, 68 arespaced apart from one another providing a gap 72, as shown in FIG. 2A.During an extreme event, such as a blade loss, the geared architecture48 may experience an extreme load in the direction F due to the fan 42rotating and attempting to move axially forward relative to otherportions of the engine 20, as shown in FIG. 2B. In such an event,extreme movements of the geared architecture 48 are limited by thecooperation of the first and second members 66, 68 such that the loadingin the direction F causes the first and second members 66, 68 to engageone another at area 74. This contact blocks movement of the gearedarchitecture 48 axially forward. Since the geared architecture 48 isconnected to the fan 42, limiting movement of the geared architecture 48may prevent the fan 42 from moving axially forward the remainingattached portions of the engine 20.

One example support assembly 64 is illustrated schematically in FIG. 3.The flex support 70 is secured to a carrier 81 by a torque frame 82. Alubrication manifold 78 is arranged axially between the carrier 81 andthe flex support 70. A geartrain 84 of the geared architecture 48 issupported by the torque frame 82. In one example, the geartrain 84 is aplanetary gear arrangement in which planetary gears are supported by thecarrier 81 and fixed against rotation by torque frame 82. A central sungear receives rotational drive from the inner shaft 40 (FIG. 1) and aring gear rotationally drives the fan 42 through the fan shaft 60 (FIG.1).

The flex support 70 includes a bellow 89, which is provided by a wallthat doubles back on itself to provide an undulation. The bellow 89accommodates a relative movement of the geared architecture 48 relativeto the engine static structure 36. An annular mounting flange 91 at anend opposite the bellow 89 is rotationally fixed relative to the enginestatic structure 36 by fasteners, splines and/or other means.

In the example illustrated, the support assembly 64 is provided by setsof first and second members 66, 68, which are removably securedrespectively to the flex support 70 and the lubrication manifold 78. Thefirst and second members 66, 68 are provided by U-shaped bracketsoriented in opposite radial positions from one another to facilitateassembly. In the example, each set of members include fivecircumferentially spaced brackets.

The support assembly 64 may be retrofitted to existing gas turbineengines with geared architectures. In one example, first and secondmachined surfaces 86, 88 are respectively provided on the flex support70 and a back side 87 of the lubrication manifold 78. If these machinedsurfaces are not provided on existing parts, the manufacturer can millthese surfaces, for example, as part of the retrofitting process. Firstfasteners 90 secure the first member 66 to the end 91. Second fasteners92 secure the second member 68 to the lubrication manifold 78 andcarrier 81. Existing geared architectures may be retrofitted byreplacing the pre-existing fasteners that secure the lubricationmanifold 78 to the carrier 81 with longer fasteners while reusingexisting holes in the carrier 81 and the lubrication manifold 78. Thefirst and second fasteners 90, 92 are threaded fasteners in one example.

Each first member 66 is provided by spaced apart legs 94 joined by abend 96. Similarly, each second member 68 is provided by spaced apartlegs 98 joined by a bend 100. The legs 94, 98 are axially spaced fromone another to provide the gap 72 during normal operation.

Referring to FIG. 4, the lubrication manifold 78 may include integrallyformed lubrication passages 79 that are cast into the lubricationmanifold 78 to provide a unitary structure. The second members 68include a second flange 104 supporting a leg 98 and secured to an outerperiphery of the lubrication manifold. Alternately, the second member 68could be secured directly to the carrier 81 through windows or scallops76 in the lubrication manifold 78. Referring to FIG. 5, the first member66 includes a first flange 102 supporting a leg 94 and secured to theannular mounting flange 91 of the flex support 70.

Referring to FIGS. 6A-7, with the first and second members 66, 68respectively are secured to the flex support 70 and the lubricationmanifold 78. The lubrication manifold 78 is arranged in a first angularposition 106, illustrated in FIGS. 6A and 6B, such that the first andsecond members 66, 68 are circumferentially adjacent to one another butmisaligned. The lubrication manifold 78 is rotated relative to the flexsupport 70 to circumferentially align the first and second members 66,68 relative to one another in a second angular position 108. In thisexample, the first member 66 includes a stop or brace 110 to strengthenthe axial retention of the member. The annular rotation is limited byexisting features, which are machined into the torque frame 82 and theflex support 70.

Features of the disclosed examples include a support structure thatpermits some movement of a geared architecture relative to otherportions of an engine during normal operation of the engine, but limitsmovements during extreme events, particularly axially forward movementsof the geared architecture.

Although an example embodiment has been disclosed, a worker of ordinaryskill in this art would recognize that certain modifications would comewithin the scope of the claims. For that reason, the following claimsshould be studied to determine their true scope and content.

What is claimed is:
 1. A support assembly for a geared architecturecomprising: an engine static structure; a flex support secured to theengine static structure and including a bellow; a support structureoperatively secured to the flex support; a geared architecture mountedto the support structure; and first members removably secured to one ofthe engine static structure and the flex support, and second membersremovably secured to the support structure, the first and second memberscircumferentially aligned with one another and spaced apart from oneanother during a normal operating condition, and the first and secondmembers configured to be engageable with one another during an extremeevent limiting axial movement of the geared architecture relative to theengine static structure in first and second axial directions that areopposite one another.
 2. The support assembly according to claim 1,wherein the flex support includes an end opposite the bellow, the firstmembers removably secured to the end.
 3. The support assembly accordingto claim 2, wherein the end is an annular mounting flange.
 4. Thesupport assembly according to claim 1, wherein the support structureincludes a torque frame and a carrier, the second members is removablysecured to at least one of the torque frame and the carrier.
 5. Thesupport assembly according to claim 4, wherein the support structureincludes an annular lubrication manifold, the second members removablysecured to the carrier and the lubrication manifold.
 6. The supportassembly according to claim 5, wherein the lubrication manifold isarranged axially between and engaging both the carrier and the secondmember.
 7. The support assembly according to claim 1, comprisingthreaded fasteners removably securing the first member and the secondmember to the flex support and the support structure, respectively.
 8. Amethod of retrofitting a support assembly to a gas turbine engine havinga geared architecture, comprising the steps of: providing attachmentfeatures in first and second structures; securing first and secondmembers respectively to the first and second structures; arranging thefirst and second members in axially interleaved spaced relation to oneanother in an installed condition; and installing the first structureonto an engine static structure and installing a geared architectureonto the second structure; wherein the arranging step includespositioning the first and second members in a first angular positionrelative to one another in a non-interleaved relationship, and rotatingthe first and second members from the first angular position to a secondangular position to interleave the first and second members, the firstand second angular positions in a common same plane.
 9. The methodaccording to claim 8, wherein the attachment features providing stepincludes providing machined surfaces on the first and second structuresthat receive the first and second members in the securing step.
 10. Themethod according to claim 9, wherein the first structure is a flexsupport having a bellow and an annular mounting flange opposite thebellow, the securing step includes mounting the first members to theannular mounting flange.
 11. The method according to claim 10, whereinthe securing step includes mounting a lubrication manifold onto thesecond structure, and securing the second members over the lubricationmanifold and in engagement with the lubrication manifold and the secondstructure.
 12. The method according to claim 11, wherein the installingstep includes securing a torque frame to the flex support and a carrier,the carrier supporting the geared architecture.
 13. The method accordingto claim 8, wherein the securing steps include tightening threadedfasteners.
 14. The method according to claim 13, wherein the securingstep relating to the second members includes selecting fasteners havinga length longer than a length of pre-existing fasteners at theattachment features, which are removed during retrofitting.
 15. A gasturbine engine comprising: an engine static structure; a flex supportsecured to the engine static structure and including a bellow; a supportstructure operatively secured to the flex support; a geared architecturemounted to the support structure; a fan section operatively coupled tothe geared architecture; and first members removably secured to one ofthe engine static structure and the flex support, and second membersremovably secured to the support structure, the first and second memberscircumferentially aligned with one another and spaced apart from oneanother during a normal operating condition, and the first and secondmembers configured to be engageable with one another during an extremefan section event limiting axial movement of the geared architecturerelative to the engine static structure in first and second axialdirections that are opposite one another.
 16. The gas turbine engineaccording to claim 15, comprising low and high spools, low pressurecompressor and turbine sections mounted on the low spool, and highpressure compressor and turbine sections mounted on the high spools, thelow spool operatively coupled to the geared architecture.
 17. The gasturbine engine according to claim 15, wherein the geared architecture isa planetary gear train.
 18. The gas turbine engine according to claim15, wherein the fan section includes a fan shaft supporting a fan, thefan shaft supported relative to the engine static structure by bearings.19. The gas turbine engine according to claim 15, comprising threadedfasteners removably securing the first member and the second member tothe flex support and the support structure, respectively.
 20. An enginesupport assembly, comprising: an engine static structure, and a supportstructure operatively mounted to the static structure and supporting amovable engine component; first and second members that arecircumferentially aligned and respectively connected to the enginestatic structure and the support structure; wherein an aft facingsurface of the first member axially opposes and is biased axially awayfrom a forward facing surface of the second member, thereby limitingaxial movement of the movable engine component relative to the enginestatic structure.
 21. The engine support assembly according to claim 20,wherein the movable engine component is a geared architecture.
 22. Theengine support assembly according to claim 20, comprising a bellowsconnected to the engine static structure for biasing the first memberaway from the second member.